On Fri, Jun 8, 2018 at 3:24 AM, Owayss Kabtoul <owayssk@xxxxxxxxx> wrote:
Hi folks,I ran into an issue where, on Postgres instances that have a very large number of databases per cluster (~15K), the autovacuum process seems to have a very high impact on CPU usage. Specifically, it is the autovacuum launcher process, not the workers. The launcher process eats a whole CPU (attached is in screenshot of htop)....So auto-vacuum never really sleeps. Even changing the autovacuum_naptime and setting it to a much higher value (from 1min to 50min) did not have any effect at all.
After changing autovacuum_naptime, did you give it enough time to stabilize at the new setting? Say, at least 3 * 50 = 150 minutes?
But overall, I would say that if you want to have 15,000 databases, you should just resign yourself to having one CPU dedicated to this task.
Cheers,
Jeff
